Method and device for positionaldeterminationof user appliances in a radio communication system using additional positional elements in neighbouring radio cells

ABSTRACT

A method and system are provided for positional determination of at least one user appliance in a radio communication system, which includes a number of base stations for dividing into radio cells, in which at least one localization measuring signal is transmitted by at least one positional element from at least one radio cell adjacent to the radio cell in which the user apparatus is located.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a method for determining theposition of at least one subscriber device of a radio communicationsystem which has a number of base stations respectively associated witha number of radio cells, with at least one locating measuring signalbeing transmitted by at least one additional position element.

[0002] In radio communication systems, such as, for example, thoseaccording to the GSM or UMTS standard, it may, if appropriate, be ofinterest to determine the current location of a specific subscriberdevice; in particular, a mobile radio device. The requirement of theposition of the respective subscriber device to be determined may arisefrom the respective subscriber himself/herself, from another subscriberor from the network infrastructure side.

SUMMARY OF THE INVENTION

[0003] The present invention, therefore, is directed toward a method andsystem in which the position of the respective subscriber device in aradio communication system can be determined as efficiently as possible.This is achieved in a method of the type mentioned at the beginning, andin an associated system, by virtue of the fact that at least onelocating measuring signal is transmitted by at least one positionelement from at least one radio cell which is adjacent to the radio cellin which the subscriber device to be respectively located is present,and is used to determine the position of the subscriber device in theradio cell in which it is located at that particular time. As a resultof the fact that in each case at least one locating measuring signal istransmitted by at least one position element in one or more neighboringradio cells, it is not necessary for position elements to beadditionally provided in the radio cell in which the actual subscriberdevice to be located is present at that particular time. This permitseffective utilization of any position elements which are alreadypresent. Supplementary applications for the radio network infrastructurecan thus be dispensed with.

[0004] Additional features and advantages of the present invention aredescribed in, and will be apparent from, the following DetailedDescription of the Invention and the Figures.

BRIEF DESCRIPTION OF THE FIGURES

[0005]FIG. 1 is a schematic view of a number of radio cells of a radiocommunication system in which the position of a mobile radio devicewhich is to be located can be determined according to a first embodimentof the method according to the present invention only using positionelements in radio cells which are adjacent to the radio cell in whichthe mobile radio device to be located is present at that particulartime.

[0006]FIG. 2 is a schematic view of a radio cell of a radiocommunication system in which position elements arranged in the radiocell can be used in a known fashion to determine the position of amobile radio device which is located therein.

[0007]FIG. 3 is a schematic view of a second embodiment of the methodaccording to the present invention for determining the position of asubscriber device of the radio communication system according to FIG. 1.

[0008]FIG. 4 is a schematic view of the further components of the radiocommunication system according to FIG. 1.

[0009]FIG. 5 is a schematic view of the chronological structure of atime frame of the radio signaling on the air interface between a basestation and a subscriber device, to be located, of the radiocommunication system according to the present invention, in accordancewith FIGS. 1 and 3, with a locating measuring signal from at least oneposition element of at least one of the adjacent radio cells having beeninserted into this free signal section of a time slot of this time frameaccording to the method of the present invention.

[0010] Elements with the same functioning and method of operation arerespectively provided with the same reference symbols in FIGS. 1 to 5.

DETAILED DESCRIPTION OF THE INVENTION

[0011] The functional components of a cellular radio communicationsystem MCS are illustrated schematically in FIG. 4, in whichtelecommunication signals are transmitted via at least one predefinedair interface (LS1) between at least one subscriber device, inparticular a mobile radio device such as, for example, UE1, and at leastone base station such as, for example, NB, SB using a time-divisionmultiplex multiple-access transmission method. The system is preferablyembodied as a mobile radio system according to the UMTS (UniversalMobile Telecommunication System) standard. Here, telecommunicationsignals are transmitted via the respective air interface, in particularin accordance with a combined TDMA/CDMA multiple-access transmissionmethod (TDMA=Time Division Multiple Access; CDMA=Code Division MultipleAccess). In particular, it is operated in what is referred to as the TDD(Time Division Duplex) mode. In the TDD mode, a separate signal fortransmission is brought about in the uplink and downlink directions(Uplink=signal transmission from the mobile radio device to therespective base station, Downlink=signal transmission from therespectively assigned base station to the mobile radio device) via acorresponding, separate allocation of time slots using a time-divisionmultiplex method. Here, preferably only a single carrier frequency isused for signal transmission in the uplink and downlink directions. Inorder to be able to bring about subscriber separation, thetelecommunication signals are, expressed in simple terms, divided overtime into a number of successive time slots with a predefinable timeperiod with a predefinable time frame structure during the radiotransmission via the air interface of the respective subscriber deviceto the assigned base station (and visa versa). A number of subscribers,which communicate simultaneously in the same radio cell with therespectively associated base station, are separated, in combination withthe time multiplex division, from one another in terms of theirtelecommunication/data connections via orthogonal codes; in particular,using what is referred to as the CDMA (Code Division Multiple Access)method.

[0012] The subscriber devices provided are preferably mobile radiotelephones; in particular, mobile phones. In addition, it is alsopossible for other telecommunication and/or data transmission deviceswith assigned radio unit (transmitter and/or receiver unit) such as, forexample, an internet computer, television sets, notebooks, fax machines,etc., to be embodied for “on air” communications traffic (i.e., via anair interface), and for them to be components of the radio communicationnetwork. The subscriber devices may, if appropriate, also be arrangedhere in a stationary, or fixed, fashion in the radio network.Preferably, they also may be of portable design and thus can be mobile;i.e., be used in different locations.

[0013] The cellular mobile system MCS usually has a number of basestations which are each assigned mobile radio cells; i.e., each basestation produces one radio cell and supplies it, in terms of radiotraffic, via at least one air interface. Within such a radio cell, itsbase station is therefore respectively responsible for communicationwith a subscriber device which is respectively present therein. Therespective base station is preferably arranged approximately in thecenter of its radio cell.

[0014] Here, in the exemplary embodiment in FIG. 4, only two basestations NB, SB are shown for the sake of clarity, the base stationsbeing representative of the number of other base stations which arepresent in the radio network. A subscriber device UE1 which is to belocated is present in the radio cell of the base station SB. Inparticular, the subscriber device UE1 (User Equipment) expressed ingeneral terms, is a physically mobile, (i.e., portable) terminal, fortelecommunication. A base station is in each case a network componentwhich serves and, if appropriate, monitors mobile terminals in a mobileradio cell of at least one air interface.

[0015] The base station SB in FIG. 4 is that network component which iscurrently serving and monitoring the mobile terminal UE1 to be locatedin the radio cell in which it is present at that particular time; i.e.,a serving mobile radio cell), via the air interface LS. The basestations such as, for example, NB, SB can in turn be combined intogroups and connected via a fixed network connection lub to a subordinatenetwork unit SRNC (Serving Radio Network Controller) which, using aprotocol RRC (Radio Resource Control=protocol for transmitting messagesbetween a mobile subscriber device and Serving Radio NetworkController), organizes and monitors the communication/data trafficbetween the respective mobile subscriber device and the respectivelyassigned base station. What is referred to as a Serving Radio NetworkController is, therefore, a network component for serving and monitoringone or more base stations which are called NodeBs in UMTS. Therespective Serving Radio Network Controller and the base stationsassigned to it form what is referred to as a Radio Network System (RNS).

[0016] A number of RNS systems are, in turn, combined in UMTS to form alogic system unit UTRAN (Universal Terrestial Radio Access Network). Theswitching unit 3GMSC (3rd Generation Mobile-services Switching Center)establishes the interface between the radio system MSC and fixednetworks such as, for example, PLMN (Public Land Mobile Network) via afixed link Iu. The MSC carries out all the necessary functions relatingto this for circuit switched services from and to the mobile stations. Acommunications link for an external location application (e.g., positiondetermining) or an external location client (LCS client) is madepossible via a connection unit GMLC (Gateway Mobile Location Center).This connection unit GMLC is connected to what is referred to as a “HomeLocation Register” HLR to which a mobile user is assigned for protocoland monitoring purposes (e.g., user information). An external locatingunit such as, for example, a LCS client ELCS (location services)application system (e.g., emergency call centers, monitoring centers,position-dependent information services) can enter into contact with theradio communication system MCS via the connection unit GMLC.

[0017] In the traffic state which is given by way of example in FIG. 4,the mobile radio device UE1 has already set up an active, existingcommunication link to the base station SB in the radio cell in which itis located at that particular time. As a result, telecommunicationsignals or data signals can be transmitted both from the base station SBto the mobile radio device UE1 (=downlink) and from the mobile radiodevice UE1 to the base station SB (=uplink). An evaluation/arithmeticunit AE (shown by dot dashed lines) is connected to the base station SBusing network elements which are not shown in FIG. 4 for the sake ofclarity. The unit AE can be used to carry out the calculation ordetermination of positions (PCF=Position Calculating Function) of themobile radio device UE1 on the basis of the measurement data. Thisevaluation/calculation unit AE also may be implemented as a component ofthe respective base station and/or in the mobile radio device UE1itself.

[0018] According to one mobile radio standard of the third generation,such as UMTS (see WCDMA for UMTS—Radio Access for Third GenerationMobile Communications: H. Holma, A. Toskala; John Wiley & Sons, NewYork; ISBN 0-47172-051-8; 2000), the position of a mobile radio devicecan be determined using the support of what are referred to as positionelements. More details on this are given in 3G TSGR1#8(99)g57:Positioning method proposal, PANASONIC, New York (USA), TSG RAN1Meeting#8, 12-15.10.1999, 3G TSGR2#8(99)e48: Positioning methodproposal, PANASONIC, Cheju (Korea), TSG RAN2 Meeting#8, 2-5.11.1999 and3G TSGR2#15-R2-001718: Assessment procedure for the OTDOA-PE positioningmethod, PANASONIC, Sophia Antipolis (France), TSG RAN2 Meeting#15,21-25.8.2000.

[0019]FIG. 2 shows, by way of example, the radio cell CE1 from thenumber of radio cells of the radio communication system according toFIG. 4. This individual radio cell CE1 is supplied, in terms of radioequipment, by the approximately centrally arranged base station NB1.Expressed in general terms, in a cellular mobile radio system such as,for example, UMTS, base stations or NodeBs produce associated,individually assigned mobile radio cells. Within a mobile radio cell, asubscriber device can have a radio link to the base station whichproduces this cell. A number of other radio cells are thus adjacent tothe respective radio cell such as, for example, CE1, the radio cellseach being produced by an individual base station. These have beenomitted in FIG. 2 for the sake of simplicity. In order to be able todetermine the position, or location, of the mobile radio device UE1which is present in the radio cell CE1 at a given time, in each case oneor more position elements such as, for example, PE11 to PE14 areadditionally arranged distributed in the respective individual radiocell such as, for example, CE1 itself.

[0020] The position elements are preferably placed in the region of theexternal boundaries of the radio cell CE1. In order to determine theposition of the mobile radio device UE1, on the one hand, the basestation NB1 itself transmits, via its air interface LS1, one or morelocating measuring signals whose transit time is measured for itstransit path to the mobile radio device UE1, and determines therefrom adistance circle RTK1 around the base station NB1 as a center point (whatis referred to as RTT (round trip time) measurement). The mobile radiodevice UE1 is located on this circle RTK with a constant radius. On theother hand, in order to further delimit its location, one or morelocating measuring signals are transmitted simultaneously, or eachoffset chronologically by a known time period, by at least two furtherposition elements such as, for example PE1 and PE3. At least two furtherdistance circles CI1 and CI3 are determined via the mobile radio deviceUE1, using corresponding transit time measurements of these locatingmeasuring signals. Here, the distance circle CI1 characterizes thoselocations at which a locating measuring signal of the position elementPE1 has in each case, the same transit time for its transit path to themobile radio device UE1. The distance circle CI2 describes thoselocations at which a locating measuring signal of position element PE2has, in each case, the same transit time for its transit path to themobile radio device UE1. Only the point of intersection of all threedistant circles RTK1, CI1, CI2 gives the location of the mobile radiodevice UE1 unambiguously.

[0021] The position elements PE11 to PE14 are expediently synchronizedwith respect to the timing pattern of the radio signaling on the airinterface LS1 of the base station NB1. This is because, in this way, thestarting time of the locating measuring signals of the position elementsis defined unambiguously, which facilitates the evaluation of thetransit times of the locating measuring signals.

[0022] Instead of the distance circles RTK1, CI1, CI2 and/or incombination with them, it is also possible to determine local hyperbolason the basis of the transit time of the locating measuring signals, asin what is referred to as the OTDOA (Observed Time of Arrival) method.More details on this known OTDOA position element measuring method(OTDOA=Observed Time Difference of Arrival) can be found in 3GTSGR1#8(99)g57: Positioning method proposal, PANASONIC, New York (USA),TSG RAN1 Meeting#8, 12-15.10.1999, 3G TSGR2#8(99)e48: Positioning methodproposal PANASONIC, Cheju (Korea), TSG RAN2 Meeting#8, 2-5.11.1999, 3GTSGR2#15-R2-001718: Assessment procedure for the OTDOA-PE positioningmethod, PANASONIC, Sophia Antipolis (France), TSG RAN2 Meeting#15,21-25.8.2000. The determination of the position in accordance with theOTDOA method is based, in particular, on measurement of signals of theair interface between a number of base stations (NodeBs) and/or positionelements in the respective radio cell in which a subscriber device ispresent, and the subscriber device which is to be respectively located.According to this method, the subscriber device which is to be locatedattempts to detect at least one pair of a known signal, for example fromtwo adjacent base stations at different locations, and/or positionelements within the respective radio cell in which a subscriber deviceis present. The reception times of the signal of two adjacent NodeBswhich are at different locations and/or position elements of the sameradio cell in which the subscriber device is present are then preferablytransmitted, for evaluation purposes, to the respective evaluation unitPCF (Position Calculation Function) of that base station (Serving NodeB)which is responsible for the subscriber device to be located. Evaluationrefers to the PCF forming the difference between the reception times ΔT.This ΔT describes a hyperboloid which specifies that the location inwhich the subscriber device to be located is present is on a hyperbola(see Taschenbuch der Mathematik: I. N. Bonstein, K. A. Semendjajew, G.Musiol, H. Muhlig; Verlag [publishing house] Harri Deutsch; 4th edition:1999). As a result of at least one further adjacent base station and/orone further position element of the same radio cell in which asubscriber is present being included, the location in which thesearched-for subscriber device is present is, thus, on one of the twopoints of intersection of two hyperbolas. A further item of informationis also necessary for an unambiguous determination position. Forexample, it is possible either:

[0023] a) to determine an OTDOA measurement with respect to a fourthNodeB and/or with respect to a further position element of the sameradio cell in which the subscriber device is present (results in a thirdhyperbola); and/or

[0024] b) in cells with sectorization, the information relating to thesector in which the subscriber device is located can be used to arriveat a decision; and/or

[0025] c) an RTT measurement can be carried out.

[0026] The locating measuring signal which is to be respectivelydetected may be the signal of what is referred to as the CPICH (CommonPilot Channel) which is continuously transmitted by the NodeBs. In orderto distinguish between the CPICH signals, each NodeB and/or eachposition element is expediently assigned a different spread code. Assuch, it is possible to differentiate the received CPICH signals, toassign them to the corresponding NodeBs or position elements, and tocalculate the necessary time differences.

[0027] The synchronization of the NodeBs with one another alsoinfluences the calculation of positions. Here, the PCF is informedwhether the NodeBs are synchronized. If they are not, it is advantageousfor the chronological shift which is present between the individualNodeBs to be signaled to the adjacent base stations. Possiblechronological shifts with respect to the transmission times can then beincluded in the calculations for the sake of correct calculationprocesses. The background to this is that, for the calculation ofposition, it is thus possible to assume that the locating measuringsignals from the various base stations have been output into the networkat approximately the same time. Using the OTDOA method, anaccuracy inthe position determination of the UE of approximately 80-100 m ispreferably obtained.

[0028] In an expansion of the OTDOA method for the case in which thesignals of the NodeB which serves the UE overlap with the locatingmeasuring signals of the other NodeBs, in what is referred to as theOTDOA-IPDL method (Observed Time Difference of Arrival-Idle PeriodDownlink), the transmissions of the NodeB (which are used by the UEwhich is to be located—referred to as serving NodeB), are switched offfor short time periods, IPDLs. Otherwise, a detection of the respectiveCPICH signal of other NodeBs would in fact be made more difficult andeven be impossible over wide parts of the mobile radio cell. Theseadditionally inserted pauses in relation to the transmission of thisNodeB can then be utilized by the UE in order to detect the receptiontimes of the CPICH signals of the adjacent NodeB. This pause (idleperiod) may be several symbols long, generally 5-10 symbols. Here, thelength of one symbol corresponds, for example, in the FDD mode of UMTSto 256 chips, and in the TDD mode to a max of 16 chips, 1 chip beingapproximately 0.26 μs long (given a chip frequency of 3.84 Mchips/s).Owing to the introduction of the IPDLs and, thus, the deactivation ofthe transmission of signals of the NodeB of interest, a capacity loss orinformation loss occurs in the corresponding mobile radio cell for thetime of the IPDLs. Using the OTDOA-IPDL method, an accuracy in thedetermination of position of up to approximately 20 m is obtained. Acorresponding procedure is also preferably adopted if position elementsare additionally used in the respective radio cell in which the deviceis present at that particular time.

[0029] The number of position elements is defined by the networkoperator in accordance with the local conditions of the respectivemobile radio cell and the required accuracy of the determination ofposition for each individual radio cell. With the previous locatingmethod, it is only possible with the PEs to use, forposition-determining purposes, the signals of only that mobile radiocell in which the mobile radio device to be determined is located atthat particular time. Signals from other NodeBs (in the adjacent mobileradio cells) for the OTDOA evaluation are basically no longer necessarybut can, of course, be used nevertheless when they are present anddetected. The insertion of IPDLs is no longer absolutely necessary,something which avoids the capacity loss of the cell which is mentionedin the OTDOA-IPDL method (see above).

[0030] Theoretically, in this method IPDLs also can increaseinaccuracies further. The PEs have two main functions:

[0031] a) they listen to the mobile radio cell traffic in the DL(down-link), to the transmission from the NodeB to the UEs; and

[0032] b) they each transmit a predefined signal code, assigned to eachPE, to the UEs in the DL.

[0033] The listening and transmitting are each carried out at afrequency, the downlink frequency of the mobile radio cell (servingcell); for example, the frequency of the broadcast channel BCH. However,both operations, of listening and transmitting, are separated from oneanother chronologically so that overlapping cannot and should not occur.

[0034] If a request for position determination of a subscriber device(UE) is present in a cell, the PEs which are respectively present in themobile radio cell are informed by the serving NodeB (via highersignaling layers or via the BCH), to transmit their assigned signal codein a specific downlink slot (DL slot). The transmission takes place atspecific times and in specific, free signal sections of the DL slot ofthe transmission signal of the serving NodeB to the UEs; i.e., the PEsplace their uniquely defined signal code sequences in signal sections,predefined by the serving NodeB, of the signaling of the serving NodeBto the UEs of this mobile radio cell (see PS1 in FIG. 5). It ispossible, for example, for these to be signal sections of the BCH whichare not used by it or signal sections in the data parts such as, forexample, DA1 of a slot (time slot) such as, for example, SLi. The UEwhich is to be located is, of course, also aware of the signal sectionsin which the PEs transmit their signal codes. As a result, the UE canattempt, in accordance with the signaling time, to detect the signalcodes of the PEs in the specific part of the DL slot and in doing sodetermine the arrival times of the signal codes. The further procedureand determination of the position takes place in accordance with theOTDOA method specified above, according to FIGS. 2 and 4.

[0035] To summarize, the essence of this known position-determiningmethod is that one or more position elements (PE), with whose supportposition determinations can be carried out according to the principle ofthe OTDOA method, are introduced per mobile radio cell. The number ofposition elements is defined by the network operator, preferably inaccordance with the local conditions (for example, topography) of therespective mobile radio cell and the required accuracy of the positiondetermining process.

[0036] With the PEs it is possible to use, for position-determiningpurposes, the signals of only that mobile radio cell in which the UE tobe determined is present. Signals of other NodeBs (in the adjacentmobile radio cells) for the OTDOA evaluation are basically no longernecessary. However, they also can, of course, be used if they arepresent and detected.

[0037] In the PE method which is described above, PEs can be introducedinto each mobile radio cell. The decision in this respect is taken bythe mobile radio network operator. Various points are to be taken intoaccount here:

[0038] 1) Number of the PEs in view of costs:

[0039] a) PEs are to be seen, depending on their method of operation, as“slimmed down” or very simple mobile radio devices with the minimumfunctions of listening to a frequency and transmitting a fixed signalcode into the mobile radio space at one frequency.

[0040] b) Despite “slimming down” (reduced functionality), the PEsentail specific costs (procurement, energy consumption, location).

[0041] 2) Use as a supplement to the NodeBs for covering only specificregions with the PEs so that PEs possibly are not present in each mobileradio cell but rather only in specific regions, for example:

[0042] a) Indoor areas

[0043] b) gaps between tall buildings

[0044] c) mountainous countryside

[0045] 3) geographic and/or legal conditions in the mobile radio cell;for example, possible prohibition against installing PEs.

[0046] A further problem is the possible, if not proven, health risks ofmobile radio waves in heavily populated areas or the like. For all theabovementioned reasons, it is acceptable or imaginable that PEs of thecellular radio communication network will not be present in each mobileradio cell. This could then have negative effects in terms of thedetermination of the position of one or more UEs and its accuracy in thethese mobile radio cells which are without position elements.

[0047] Despite these conditions (i.e., mixture of radio cells with andwithout additional position element), it is possible to carry out thedetermination of the position of a subscriber device over a large areaby using the locating measuring signals of one or more position elementsin adjacent radio cells for evaluation in those radio cells in which noposition elements, or too few position elements, are present. In otherwords, use is made of PE elements in radio cells which are adjacent tothe radio cell in which the subscriber device to be respectively locatedis present at that particular time (but without support, or withinsufficient support by position elements in the radio cell (servingcell) in which the UE to be located is present at that particular time(see FIGS. 1 and 3). For the case just mentioned in which PEs are notpresent or there is an inadequate supply of PEs in the respectiveserving cell, one or more PEs are, therefore, stationed in one or moreadjacent cells and their locating measuring signals are used for thedetermination of position. As a result, such gaps in provision areclosed.

[0048] As the assignment of the maximum 240 signal codes (in particular,the 240 unused S-SCH codes (Secondary Synchronization Channels); inUMTS, of 256 channels made available only 16 are allocated and used) tocorresponding PEs of the mobile radio network is known in advance to theUEs via the BCH (transmitted by the NodeBs or the higher signalinglayers in the case of, for example, the first radio contact=logging on),it is possible for the UEs in the serving cell to listen to the signalcodes of the PEs from the adjacent cells.

[0049] The quintessence of the solution to the above problems is, inparticular, the use of position elements of the adjacent cells in theserving cell, or preferably via the uniquely defined signal codes whichare assigned to them and known in advance, for determining the positionof UEs in the serving cell. The determination of the positionadvantageously can be carried out here in accordance with the OTDOAmethod.

[0050] In this way, on the one hand, the costs of the network operatorscan be reduced by virtue of a smaller number of necessary positionelements in the radio communications network. Adverse effects in termsof the availability and accuracy of the determination of position arethus, largely avoided. A further advantage is that failure times of PEsof whatever kind in the serving cell can be compensated using PEs in theadjacent mobile radio cells. Position calculations, therefore, continueto be possible. A main advantage is, in particular, the more effectiveplanning of the locations of the PEs. Associated with this are thealready-mentioned savings in PEs in the entire network. The locations ofthe PEs can be particularly selected such that, in the one mobile radiocell, PEs are located more toward the edge of the cell, and in theadjacent cells they are located more in the direction of NodeB or morein the direction of the local features which cause problems in terms ofthe geographic conditions (see FIG. 3). With the use of PEs from theadjacent mobile radio cells it is also possible to avoid, decrease orattenuate geographic, legal or health problems relating to theinstallation of PEs in some mobile radio cells.

[0051] With the present method it is possible to dispense with IPDLs (asin the OTDOA-IPDL method). As a result, the loss of capacity can beavoided because of possible IPDLs. Therefore, it is possible for thenetwork operator to reach his/her target capacity, even with the feature“determining the position of UEs.”

Exemplary Embodiment 1

[0052] In the first exemplary embodiment, FIG. 1 serves as a basis forthe explanations. It is assumed that, by way of example, four basestations NB1, NB2, NB3 and NB4 cover the UMTS mobile radio cells CE1,CE2, CE3 and CE4. Further adjacent cells will not have any role in thefirst exemplary embodiment, for the sake of clarity. These NodeBs aremonitored and served by a RNC, thus giving rise to a system includingmonitoring element, base stations, mobile radio device and positionelements (the RNC is the superordinate monitoring unit for a specificnumber of NodeBs and is not explicitly specified in FIG. 1).

[0053] Furthermore it is assumed that a mobile radio device UE1 which isto be located is present in the UMTS mobile radio cell CE1 (the servingcell) and is supplied or served by this base station or NodeB NB1. Here,it is not relevant whether the interrogation as to the determination ofthe position starts from the mobile radio device UE1 or from the networkand, thus, from any interrogating client in the network.

[0054] The hexagonal mobile radio cell which is shown in FIG. 1represents an abstraction for the sake of better presentation of thearrangement of a mobile radio cell and its elements.

[0055] Furthermore, a certain number of PEs are present in the adjacentmobile radio cells CE2, CE3 and CE4, while no position elements arepositioned in the radio cell (serving cell) CE1 in which the device ispresent at that given time. In detail, the additional position elementsPE21, PE22 are arranged in the adjacent radio cell CE2, the positionelements PE31, PE32 in the adjacent radio cell CE3, and the positionelements PE41, PE42 in the adjacent radio cell CE4. The PE distributionin the mobile radio cells CE2, CE3 and CE4 is performed in such a waythat the locating measuring signals of the PEs of these adjacent radiocells, in this example the UMTS mobile radio cells CE2, CE3 and CE4, canbe satisfactorily “heard” (i.e., detected), in the serving cell of thesubscriber device UE1 to be located. In general, this refers to the PEspreferably being stationed in the vicinity of the cell boundary, near tothe serving cell. Here, the distribution is preferably configured suchthat the locating measuring signals of all the PEs in total cover, asfar as possible, 100% of the UMTS mobile radio cell CE1 in which thedevice is located at that particular time.

[0056] If, for example, the subscriber device UE1 which is to be locatedis present in the mobile radio cell CE1 near to its upper left-handcorner, it is possible that the subscriber device UE1 can evaluatemeasurement signals of the position elements PE21 and PE42 during aposition interrogation. On the other hand, problems will and can occurwith respect to the detection of the locating measuring signals of theother PEs (PE31, PE32, PE41) because these PEs are difficult for thesubscriber device UE1 to be located to detect, or cannot be detected atall. The reasons are the relatively large distances and, as a result,weaker signal powers and possibly a greater quantity of shadowing in thedistance between these PEs and the subscriber device UE1.

[0057] If the subscriber device UE1 is, according to FIG. 1,approximately in the center of the right-hand half of the UMTS mobileradio cell CE1, it is possible for it to detect the signal codesequences of the position elements PE21, PE31, PE32 and PE42 of theadjacent radio cells CE2, CE3, CE4 to a degree lying betweensatisfactory and very satisfactory, while the position element PE42 isalready too far away for sufficiently good reception. A possiblesequence for the determination of the position of the subscriber deviceUE1 could be, by way of example, as follows:

[0058] The position of the subscriber device UE1 in the UMTS mobileradio cell CE1 is to be determined; it is not relevant here why therewas a position interrogation or where it came from. Owing to theposition-determining accuracy which is defined in the requirements, theRNC will decide to use position elements (PEs). After this, the basestation NB1 of the radio cell CE1 in which the device is present will beinformed by the RNC. Via the BCH, radio cell CE1 informs the PEs of theadjacent mobile radio cells, CE2, CE3 and CE4 of the positioninterrogation and the times at which the respective position elementinserts its signal code sequence, assigned to it, into the DL slotstructure of the NodeBs NB1 for the subscriber device UE1. In the firstinstance, the fact that the PEs are situated in the vicinity of the cellboundary of the UMTS mobile radio cell CE1, and thus also receive the DLtraffic, ensures that the position elements (PEs) in the adjacent cellsare provided with this information. In the second instance, the RNCensures that the adjacent NodeBs also integrate this information intotheir DL traffic. The subscriber device UE1 is also provided with thisinformation as the DL link of the serving nodeB NB1 also hears this. Atthe given times, the position elements PE21, PE31, PE32 and PE41 theninsert their signal code sequences into the respective DL slotstructure. The subscriber device UE1 then attempts to determinereception times of the code sequences using the knowledge of the signalcode sequences and of the associated position element (via, for example,a rake receiver (i.e., correlation receiver), with which time shifts canbe determined by correlations). This information is transmitted by thesubscriber device UE1 to the serving nodeB NB1. From this, nodeB NB1then determines time differences between the reception time points ofthe PE signal code sequences. These differences are mapped ontohyperbolas using the OTDOA method; the common point of intersection ofthe hyperbolas is the searched-for position in an accuracy value rangewhich is dependent on the surroundings.

Exemplary Embodiment 2

[0059] Exemplary embodiment 2 is related entirely and completely to theabove exemplary embodiment 1 and relates to FIG. 3 instead of FIG. 7.The difference is the expansion to 6 UMTS mobile radio cells (CE1 toCE6), and the changed number of PEs and their assignment. There are nowthree position elements present: PE32 in UMTS mobile radio cell CE3,PE41 in UMTS mobile radio cell CE4, and PE61 in UMTS mobile radio cellCE6. There are no position elements in the UMTS mobile radio cells CE2and CE5, or in the UMTS radio cell CE1 in which the device is present atthat particular time. Here, the following is to apply:

[0060] 1) The position element PE61 (in UMTS radio cell CE6), PE41 (inUMTS radio cell CE4), and PE32 (in UMTS radio cell CE3) together coverthe UMTS cell CE1 in terms of radio equipment.

[0061] 2) The position element PE61 (in UMTS radio cell CE6), PE41 (inUMTS radio cell CE4), and PE32 (in UMTS radio cell CE3) alsorespectively cover their own mobile radio cell to a certain extent.

[0062] 3) The position element PE61 (in UMTS radio cell CE6)additionally covers the upper part of the UMTS radio cell CE5.

[0063] 4) The position element PE41 (in UMTS radio cell CE4)additionally covers the lower part of the UMTS radio cell CE3 and UMTSradio cell CE5.

[0064] 5) The position element PE31 (in UMTS radio cell 3) additionallycovers the lower part of the UMTS radio cell CE2.

[0065] The position of the subscriber device UE1 is determined in a waywhich is analogous to the descriptions in exemplary embodiment 1.Exemplary embodiment 2 is intended to clarify, in particular, that adifferent number and arrangement of the position elements (PEs) does notresult in any fundamental difference.

Exemplary Embodiment 3

[0066] Exemplary embodiment 3 relates entirely and completely to the twoprevious exemplary embodiments 1 and 2. The difference or the expansionis the use or introduction of pauses in the DL traffic of the NodeB NB1to the subscriber device UE1 to be located. In specific terms, thismeans: for the signal code sequences of the PEs of the adjacent UMTSmobile radio cells (CE2 to CE6 in FIG. 3) to be able to be detectedlargely without any disruptive influences of the NodeB NB1, the DLtransmission from the NodeB NB1 to the subscriber device UE1 is switchedoff for a specific time period, referred to as idle periods. All thecorresponding PEs then transmit their signal code sequences precisely inthis idle period. The information about the idle period is also providedvia the BCH channel. This thus increases the probability of thesubscriber device UE1 to be located detecting the corresponding PEs asfar as possible (i.e., as far as possible by 100%), and in addition,under certain circumstances, detecting signals from other, more distantPEs. The result would be a qualitatively better determination ofposition.

[0067]FIG. 5 shows in a schematic view the chronological structure of atime frame FRi of the radio signaling on the air interface LSi betweenthe base station NB1 and the mobile radio device UE1 to be located, inFIG. 1. Here, in a free signal section of a time slot of this timeframe, a position element which is also listening in has inserted alocating measuring signal in one of the adjacent radio cells using themethod according to the present invention via either automatic selectionor defined assignment in advance. The time frame FRi of thechronological length TF has a number of individual, chronologicallysuccessive time slots SL0 to SL14 of respectively the same, constanttime period. Such time frames in such a context follow one another insuccession; i.e., continuously during the telecommunicationstransmission. This is indicated in FIG. 5 by, in each case, three pointsat the start and end of the time frame FRi. The structure of the timeframe FRi preferably corresponds to the slot structure of what isreferred to as a TDD frame (TDD=Time Division Duplex). A TDD frame suchas, for example, FRi is preferably composed here of a total of 15 timeslots SL0 to SL14. Here, each time slot can be allocated (i.e., reservedor made available), in a uniquely defined way either for transmissionsin the uplink traffic or downlink traffic.

[0068]FIG. 5 shows a schematic view of the chronological configurationor the structure (i.e., the chronological division of a time slot) suchas, for example, SLi of the time frame FRi. Each respective time slot,such as, for example, SLi has 4 time sections DA1, MI, DA2, PC2 whichare reserved for the transmission of various groups of signal types. Thefirst time section DA1 of the time slot SLi is preassigned for thetransmission of useful data, referred to as data symbols. Then, in thesecond, subsequent time section or block MI, what are referred to asmidambles are transmitted. These are signals for the channel estimationand/or synchronization of the respective subscriber device and/or of therespective base station. In particular channel equalization in therespective mobile radio device and/or the respective base station iscarried out on the basis of these channel estimation parameters. Thistime block MI is, in turn, followed by a time section DA2 for a furthertransmission of useful data. By virtue of the fact that the midambles ofa channel estimation are transmitted between the two blocks with theuseful data or useful signals, it is largely ensured that the respectiveradio channel can be equalized to an optimum degree when averaged overtime. During the fourth, last time section PC2 of the time slots SLi,there is finally no signal transmission; i.e., this so-called guardperiod is unassigned in order to have a safety time gap between theindividual time slots which are transmitted in chronological succession.As a result, in particular, disruptive signal superimpositions orinterference between successive slots as a result of signal transit timedifferences such as, for example, in the case of multi path propagation,are substantially avoided so that satisfactory signal detection islargely ensured. Considered overall, the radio transmission of aso-called burst with predefined chronological division or sectioningtherefore can take place during the respective time slot. Detailedinformation on the time frame structure and time slot structure aregiven in the respective mobile radio standard, particularly in the UMTSstandard here with respect to the exemplary embodiment; for example, 3GTS 25.221 “physical channels and mapping of transport channels ontophysical channels (TDD)”, version 3.2.0 (2000-03), 3G TS 25.305 “stage 2functional specification of location services in UTRAN”, Version 3.1.0(2000-03, 3G TS 25.224 “physical layer procedures (TDD)”, Version 3.2.0(2000-03).

[0069] In the exemplary embodiment here, the signaling code PS1 of oneof the position elements such as, for example, PE11 is transmitted, byway of example, during the time section DA1 in the time slot SLi of thetime frame FRi, given that a free signal section is available.

[0070] The localization method which is described, by way of example,but with reference to a UMTS radio communication system also can, ofcourse, be applied in other radio communication systems such as, forexample, ones according to the GPRS (General Packet Radio Service), orEDGE (Enhanced Data Rates for GSM Environments) standard.

[0071] Although the present invention has been described with referenceto specific embodiments, those of skill in the art will recognize thatchanges may be made thereto without departing from the spirit and scopeof the present invention as set forth in the hereafter appended claims.

1. A method (PO1) for determining the position of at least onesubscriber device (UE1) of a radio communication system (MCS) which hasa plurality of base stations (NB1 to NB4) for bringing about divisioninto radio cells (CE1 to CE4), at least one locating measuring signal(PS21, PS31, PS32, PS41) being transmitted by at least one additionalposition element (PE21, PE31, PE32, PE41, PE42) characterized in that atleast one locating measuring signal (PS21) is transmitted by at leastone position element (PE21) from at least one radio cell (CE2) which isadjacent to the radio cell (CE1) in which the subscriber device (UE1) tobe respectively located is present, and is used to determine theposition of the subscriber device (UE1) in the radio cell (CE1) in whichit is present at that particular time.
 2. The method as claimed in claim1, characterized in that the signaling on the air interface (LS1) of thebase station (NB1) of the respective radio cell (CE1) is carried outusing a time-division multiplex method, in particular using the TDD(time division duplex) mode of the UMTS (Universal MobileTelecommunication System) standard.
 3. The method as claimed in one ofthe preceding claims, characterized in that a unique identification codeis assigned to the locating measuring signal (PS21) of the respectiveposition element (PE21).
 4. The method as claimed in one of thepreceding claims, characterized in that a mobile radio device, inparticular mobile telephone, is used as the subscriber device (UE1). 5.The method as claimed in one of the preceding claims, characterized inthat the locating measuring signal (PS21) is transmitted by therespective position element (PE21) during at least one unoccupied signalsection (DA1) which is already present in the signaling traffic of thebase station (NB2) of its assigned radio cell (CE1) and/or of the basestation (NB1) of the radio cell (CE1) in which the mobile radio device(UE1) to be located is present.
 6. The method as claimed in one of thepreceding claims, characterized in that the locating measuring signal(PS21) is transmitted by the respective position element (PE21), duringits specially inserted quiescent time, into the signaling traffic of thebase station (NB2) of its assigned radio cell (CE1) and/or of the basestation (NB1) of the radio cell (CE1) in which the subscriber device(UE1) to be located is present.
 7. The method as claimed in one of thepreceding claims, characterized in that locating measuring signals of atleast two, in particular of three, position elements (PE21, PE31) areused for determining the position of a subscriber device (UE1) which isto be located.
 8. The method as claimed in one of the preceding claims,characterized in that the position elements (PE31, PE32) aresynchronized with respect to the timing pattern of the radio signalingon the air interface (LS1) of the base station (NB1) of the radio cell(CE1) in which the subscriber device (UE1) to be respectively located ispresent.
 9. The method as claimed in one of the preceding claims,characterized in that the transit time of the respective locatingmeasuring signal (PS21, PS31, PS32, PS41, PS42) for its transit pathbetween its position element (PE21, PE31, PE32, PE41, PE42) and thesubscriber device (UE1) to be respectively located is determined andmade available for evaluation.
 10. A device for determining the positionof at least one subscriber device of a radio communication system, whichis carried out according to one of the preceding claims.